Phthalocyanines were accidentally discovered in 1928. Close collaboration between chemist Reginald Patrick LINSTEAD and crystallographer J. Monteath ROBERTSON led to the determination of the molecular structure of phthalocyanine. Robertson published three phthalocyanine crystal structures (PcH2, PcNi and PcPt).
For 30 years, these were the only phthalocyanine crystal structures until mid of the 1960s computer-controlled diffractometers became available - and with it, many new structures were determined. End of the 1970s, interest in "organic superconductors" produced a renaissance in phthalocyanine crystal research. In the 1990s, research in photoconductors awakened interest in phthalocyanine crystals. At that time, I was told that the sensitivity of phthalocyanine photoconductors depend on the crystal structure but I soon found out that nobody actually knew how phthalocyanines were arranged. With this insight, I started collecting structures.
My publications on phthalocyanine single-crystal structures give an overview of all crystal structures published, paper 1 covers more than 200 structures and paper 3 covers more than 580 phthalocyanine, naphthalocyanine, subphthalocyanine, superphthalocyanine, porphyrazine and related structures.

    Chem.Abstr: 127:313213 (1998)
    Single-Crystal and Solid-State Molecular Structures of Phthalocyanine Complexes.
    Michael K. Engel, Kawamura Rikagaku Kenkyusho Hokoku (1996), 1997, 11-54 (English)

    Chem.Abstr: 130:39766 (1999)
    Synthesis, Structural Characterization and Optical Properties of Several Boron Subphthalocyanines and a Boron beta-Isoindigo Complex.
    Michael K. Engel, J. Yao, H. Maki, H. Takeuchi, H. Yonehara, C. Pac, Kawamura Rikagaku Kenkyusho Hokoku (1997), 1998, 53-65 (English)

    Chem.Abstr: 139:158830 (2003) - CAS made a very bad abstract from this 246 page review, e.g. OCRed references with many errors; many keywords are omitted, I guess, I have to write an abstract by myself
    Single-Crystal Structures of Phthalocyanine Complexes and Related Macrocycles.
    Michael Klaus Engel, in "The Porphyrin Handbook", (Eds. Karl M. Kadish, Kevin M. Smith and Roger Guilard), Volume 20 (Phthalocyanines: Structural Characterization), 2003, 1-246

If you are interested in knowing more about phthalocyanine crystal structures, I would like to draw your attention to the "Structural Chemistry of Porphyrins and Phthalocyanines" symposium at the Third International Conference on Porphyrins and Phthalocyanines (ICPP-3) (July 11-16, 2004 in New Orleans, Louisiana, U.S.A.), which I will be chairing together with Prof. Robert Scheidt from University of Notre Dame.

Phthalocyanines: From Molecular Structures to Solid-State Arrangements
Engel, Michael Klaus
Third International Conference on Porphyrins and Phthalocyanines (ICPP-3), July 11-16, 2004 in New Orleans, Louisiana, U.S.A.
invited lecture, abstract (pdf)
invited lecture (ppt)